Chapter 3 Vocabulary

Question 1

Troposphere

Answer 1

Inner layer of the atmosphere that
extends only about 17 kilometers (11 miles) above sea level at the tropics and about 7 kilometers (4 miles) above the earth’s north and south poles. It contains air that we breathe, consisting mostly of nitrogen (78% of the total volume) and oxygen (21%).

Question 2

Greenhouse gases

Answer 2

The remaining 1% of the air includes water vapor, carbon dioxide, and methane, all of which are
called greenhouse gases, which absorb and release
energy that warms the lower atmosphere.

Question 3

Stratosphere

Answer 3

The next layer, stretching 17–50 kilometers (11–31
miles) above the earth’s surface, is called the stratosphere. Its lower portion holds enough ozone (O3) gas to filter out about 95% of the sun’s harmful ultraviolet (UV) radiation.

Question 4

Hydrosphere

Answer 4

Consists of all of the water on or near the earth’s surface. It is found as water vapor in the atmosphere, liquid water on the surface and under-
ground, and ice—polar ice, icebergs, glaciers, and ice in frozen soil layers called permafrost.

Question 5

Geosphere

Answer 5

Consists of the earth’s intensely hot

core, a thick mantle composed mostly of rock, and a thin outer crust.

Question 6

Biosphere

Answer 6

Consists of the parts of the atmosphere, hydrosphere, and geosphere where life is found.

Question 7

Natural greenhouse effect

Answer 7

As this infrared radiation travels back from the
earth’s surface into the lower atmosphere, it encounters greenhouse gases such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Some of it flows back into space as heat. The rest of it causes the greenhouse gas molecules to vibrate and release infrared radiation with even longer wavelengths. The vibrating gaseous molecules then have higher kinetic energy, which
helps to warm the lower atmosphere and the earth’s surface. Without this natural greenhouse effect, the earth would be too cold to support the forms of life.

Question 8

Ecology

Answer 8

Is the science that focuses on
how organisms interact with one another
and with their nonliving environment of
matter and energy.

Question 9

Organism

Answer 9

An individual living being.

Question 10

Population

Answer 10

A group of individuals of the same species living in a particular place.

Question 11

Community

Answer 11

Populations of different species living in a particular

place, and potentially interacting with each other.

Question 12

Ecosystem

Answer 12

A community of different species interacting with one another and with their nonliving environment of
matter and energy.

Question 13

Biosphere

Answer 13

Parts of the earth’s air, water, and soil where life

is found.

Question 14

Trophic level

Answer 14

Ecologists assign every type of organism in an ecosystem to a feeding level, or trophic level, depending on its source of food or nutrients.

Question 15

Producers (autotrophs)

Answer 15

Sometimes called autotrophs (self-feeders), make the nutrients they need from compounds and energy obtained from their environment.

Question 16

Chemosynthesis

Answer 16

A few producers, mostly specialized bacteria, can convert simple inorganic compounds from their environment into more complex nutrient compounds without using sunlight.

Question 17

Photosynthesis

Answer 17

Plants typically capture about 1% of the solar energy that falls on their leaves and use it in combination with carbon dioxide and water to form organic molecules, including energy-rich carbohydrates (such as glucose, C6H12O6), which store the chemical energy they need.

Question 18

Consumers (heterotrophs)

Answer 18

(“Other-feeders”), that cannot produce the nutrients they need through photosynthesis or other processes.

Question 19

Primary consumers (herbivores)

Answer 19

(Plant eaters), are animals that eat mostly green plants.

Question 20

Carnivores

Answer 20

(Meat eaters) are animals that feed on the flesh of other animals.

Question 21

Secondary consumers

Answer 21

Some carnivores such as spiders, lions, and most small fishes are secondary consumers that feed on the flesh of herbivores.

Question 22

Tertiary consumers

Answer 22

Other carnivores such as tigers, hawks, and killer whales (orcas) are tertiary (or higher-level) consumers that feed on the flesh of other carnivores.

Question 23

Omnivores

Answer 23

Such as pigs, rats, and humans eat plants and other animals.

Question 24

Decomposers

Answer 24

Are consumers that, in the process of obtaining their own nutrients, release nutrients from the wastes or remains of plants and animals and then
return those nutrients to the soil, water, and air for
reuse by producers.

Question 25

Detritus feeders (detritivores)

Answer 25

Feed on the wastes or dead bodies of other organisms; these wastes are called detritus (dee-TRI-tus), which means debris.

Question 26

Aerobic respiration

Answer 26

Uses oxygen to convert glucose (or other organic nutrient molecules) back into carbon dioxide and water.

Question 27

Anaerobic respiration (fermentation)

Answer 27

Some decomposers get the energy they need by

breaking down glucose (or other organic compounds) in the absence of oxygen.

Question 28

Food chain

Answer 28

A sequence of organisms, each of which serves as a source of food or energy for the next.

Question 29

Food web

Answer 29

Organisms in most ecosystems form this complex network of interconnected food chains.

Question 30

Biomass

Answer 30

The dry weight of all organic matter contained in its organisms.

Question 31

Pyramid of energy flow

Answer 31

Illustrates energy loss for a simple food chain, assuming a 90% energy loss with each transfer.

Question 32

Gross primary productivity (GPP)

Answer 32

Is the rate at which an ecosystem’s producers (usually plants) convert solar energy into chemical energy in the form of biomass found in their tissues.

Question 33

Net primary productivity (NPP)

Answer 33

Is the rate at which producers
use photosynthesis to produce and store chemical
energy minus the rate at which they use some of this stored chemical energy through aerobic respiration.

Question 34

Biogeochemical cycles (nutrient cycles)

Answer 34

The elements and compounds that make up nutrients move continually through air, water, soil, rock, and living organisms within ecosystems, as well as in the biosphere in cycles called biogeochemical cycles (literally, life-earth-chemical cycles), or nutrient cycles.

Question 35

Hydrologic cycle (water cycle)

Answer 35

Collects, purifies, and distributes the earth’s fixed supply of water.

Question 36

Carbon cycle

Answer 36

Various compounds of carbon circulate
through the biosphere, the atmosphere, and parts of the hydrosphere, in the carbon cycle. The carbon cycle is based on carbon dioxide (CO2) gas, which makes up 0.039% of the volume of the earth’s atmosphere and is also dissolved in water.

Question 37

Nitrogen cycle

Answer 37

The other takes place in aquatic systems, in soil, and in the roots of some plants, where specialized bacteria, called nitrogen-fixing bacteria, complete this conversion as part of the nitrogen cycle.
The nitrogen cycle consists of several major steps. In nitrogen fixation, specialized bacteria in soil as well as blue-green algae (cyanobacteria) in aquatic environments combine gaseous N2 with hydrogen to make ammonia 3).

Question 38

Phosphorus cycle

Answer 38

Compounds of phosphorous (P) circulate through water, the earth’s crust, and living organisms in this cycle.

Question 39

Sulfur cycle

Answer 39

Sulfur circulates through the biosphere in the sulfur
cycle. Much of the earth’s sulfur is stored underground in rocks and minerals and in the form of sulfate (SO4 2–) salts buried deep under ocean sediments.

Question 40

Atmosphere

Answer 40

Is a thin spherical envelope of gases surrounding the earth’s surface.